That’s really odd. Do you have a smart plug around the house? Or a safe way to check the outlet’s voltage that you are using? Just seems super odd that 2 machines, potentially made months apart have the same fault.
I’m not sure what a 5 or 6% shortage will do to the printer (if anything), but it would be good to know that the issue isn’t a local issue disguised as a printer fault.
Ok. BTW they are lead screws (not ball screws) on these printers.
Mine are black too when I clean them after a few months when the printer asks me for it, even though I use SuperLube silicone grease with PTFE⁽¹⁾ which is translucent white out of the tube.
I don’t know why it becomes black (oxidization under heat and captured microparticles, I guess). Do you guys also get black grease on lead screws?
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¹ There are in fact two variants of this. I use SuperLube 21030, whereas SuperLube 92003 (which is heat resistant) should be better and is the one recommended by Bambu Lab. They also recommend BX-300/F(DF) Series high temperature grease with fluorine and Lucas Oil 10533 White Lithium Grease.
SuperLube 92003 is going dark too 
Welp, seems like my first layer quality went down the drain 
Guess I’ll have to troubleshoot using their Wiki article regarding first layer quality.
Yes it’s normal because of the wear down metal particles and oxidation. Don’t worry too much. Clean it when you want to
Pretty sure it’s due to the brass nut oxidation being worn off with the contact to the screw
Brass nut oxidation, it’ll get ya every time! 
I have used it on 2 separate outlets with the same result unfortunately. Both pulling the proper voltage.
0.28-0.33 is normal for most bambu pla on h2d 0.4 nozzles, it’s the same on hf nozzles as well.
I think you meant to tag someone else’s reply. Mine was about external factors (power/voltage).
@WisestMoose how’s your ambient temp? If it’s cold, try manually turning off the chamber exhaust after starting a job. Some people were having over cooling issues in cold rooms when that top vent opens and pulls cold air over the print.
In all honesty, I am not impressed with the print quality of my H2D either. I have 3 X1C’s and a P1S that all print better than my H2D. I don’t really have the time to go down the rabbit hole troubleshooting it either, which pretty much means it does nothing. A very big $2400 paper wieght… I am not happy about the purchase at this point. When I do try to print with it, it moves and shakes a whole lot more than my X1C’s, which is to be exprected, but yeah, it dances, lol.
The ambient temp is 22-23 degrees Celsius in the room. No drafts.
I have noticed very weir looking z-seams on mainly round objects with the H2D recently. Has somebody a clue what this could be.
The rest of the print looks quite nice.
This looks like underextrusion as many ppl already mentioned. What can cause this…
wrong extrusion mulitplier - check
wrong k-value - check
low temperature -
clogged nozzle - check
what you could try is up the temperature to 250 or so. Might be a faulty thermistor.
Not saying this is the solution, but just something else you can try.
I have seen this happen when ppl used a hardened steel nozzle with brass temp settings.
(do you have a hardened nozzle and this is set to in Studio? But i guess this is done automatically with the H2D)
Im having the exact same issue with hole dimensional accuracy. A 3.3mm hole in CAD comes out to ~ 2.6mm on the printer. Its practically unusable for detailed engineering applications.
You might want to do some reading up on the FDM process and its quirks.
It is as if you are laying down an elastic band, and on small holes this is the most visible.
If a 33mm hole comes out as 26mm then you got to start worrying about the quality of your printer.
I’ve been working with/working on FDM machine for years and this behavior is not representative of a well tuned machine.
Yes it’s true that dimensional inaccuracies do exist due to expansion/motion system etc. But it is not normal for a $2000 machine to be turning 3.2mm holes into 2.5mm holes when a $600 P1S and $400 A1 are able to put out holes of 3.0mm - 3.1mm given the default print profiles and the exact same filament as the H2D.
A deviation between 0.1mm - 0.3mm is acceptable and can be attributed to motion system/expansion.
A deviation of 0.7mm or greater is simply far too much to chalk up to inevitable inaccuracies, especially when cheaper machines (even a box stock ender 3) produce better results.
As for the the comment about 33mm showing up as 26mm for there to be a problem. I get what you are saying, but that’s also quite a silly hyperbole lol.
An accuracy of 0.1mm in FDM printing has been perfectly achievable for many years now. And up to 0.3mm is still acceptable in most cases. But pretending like it’s normal for a well tuned “turn key” printer to print with inaccuracies approaching 1mm is not reasonable when other machines on the market and $99 ender 3 pros will get under 0.3mm on their stock CURA profiles.
Guys If you have issues with quality, if something seems weird, check your belts. If you see them worn out already on the edges , with hair sticking out, check your Gantry leveling/belt path. Move your toolhead around and check the belts as you do. If the drift up/down on their rollers that is NOT normal and WILL cause quality issues.
Refer to this thread Normal wear? Black specks building in back left and right corners if you want to know more, I have posted a detailed text about this , what causes it , what it causes etc.
For anyone who has built their own machine will know what errors in belt path mean…
I have the same years of experience.
But the result of your printer output is defined by minimally 3 factors:
Simply stating that the printer is the issue is a bit short sighted. Even if cheaper printers do the job better.
Yesterday I printed a test cube with a poor ABS profile and the 2 walls of a 10mm hole were somehow not properly bonded to the previous layer due to too much cooling. Is the printer the issue then?
The cooling on the H2D is quite strong and needs adjusting sometimes.
